Adaptive filter with y capacitors for a 3-phase DC on-board electrical system

Abstract

The invention relates to a current converter (1, 1a, 1b) for an on-board electrical system (101) of an electrically driveable vehicle (100), comprising a first line (2) for a first potential (3), a second line (4) for a second potential (5), a third line (6) for a reference potential (7) and a filter unit (8), which has first to third connectors (10,-12) connected to the first to third line (2, 4, 6), a first and second capacitor (13, 14), between which a central node (15) is formed with a connection to the third connector (12), a third and fourth capacitor (16, 17) connected between a connector (13a) of the first capacitor (13) and the first connector (10) or a connector (14b) of the second capacitor (14) and the second connector (11), and a switch unit (19) which is designed to switch between a first and a second filter mode according to control information (20), wherein, in the first filter mode, a first current path (21) for an interference current is formed on the first line (2, 4) from the first connector (10), via the third capacitor (16), a parallel connection of the first and second capacitors (13, 14) and the central node (15), to the third connector (12), and a second current path (22) for an interference current is formed on the second line from the second connector (11), via the fourth capacitor (17), a parallel connection of the first and second capacitors (13, 14) and the central node (15), to the third connector (12), wherein, in the second filter mode, an admittance for the interference current along the first current path (21) and the second current path is at least reduced relative to the first filter mode.

Description

[0001] ADAPTIVE FILTER WITH Y-CAPACITERS FOR 3-WIRE DC ON-BOARD NETWORK

[0002] The present invention relates to a power converter for an on-board power system of an electrically driven vehicle, comprising a first line for a first potential, a second line for a second potential, a third line for a reference potential and a filter device which has a first terminal connected to the first line, a second terminal connected to the second line, a third terminal connected to the third line, a first capacitor and a second capacitor, between which a center node with an electrically conductive connection to the third terminal is formed, and a switching device which is configured to switch between a first filter mode and a second filter mode of the filter device as a function of control information.

[0003] The invention also relates to an on-board network for an electrically powered vehicle.

[0004] DE 10 2017 220 982 A1 discloses a traction network in an electric or hybrid vehicle. The traction network comprises a high-voltage battery connected to a pulse-controlled inverter via a positive high-voltage line and a negative high-voltage line. A Y capacitor is connected to each of the positive and negative high-voltage lines. A switching element is assigned to the Y capacitors, which can be controlled by a control unit depending on at least one operating state.

[0005] DE 10 2021 003 180 A1 discloses an electrical system for an electrically operated vehicle, comprising a first electrical potential line and a second electrical potential line, between which the electrical system is supplied with a direct current. The electrical system has two first interference suppression capacitors, which are electrically connected in series and are each electrically coupled to the potential lines via a terminal. The electrical system further comprises two further interference suppression capacitors and a switch.

[0006] In electrically powered vehicles, on-board electrical systems, particularly high-voltage on-board electrical systems, are typically designed as IT systems in which a first and second potential of a traction battery are isolated from a reference potential, in particular a vehicle housing potential. Power converters used in such on-board electrical systems and whose first and second lines can be connected to the first and second potential of the traction battery can generate high-frequency interference signals during operation, which must be filtered by means of a filter device for reasons of electromagnetic compatibility. Such a filter device typically has two capacitors, which serve in particular to divert a common-mode current on the first and second lines to a third line at the reference potential.

[0007] As the vehicle electrical system voltage increases, which corresponds to the difference between the first and second potentials, the amount of energy stored in the first and second capacitors of the filter device also increases with the square of the vehicle electrical system voltage. Relevant standards, such as ISO 6469-3, limit this amount of energy to a specified value. This allows the electrical charges stored in the capacitors and dissipating via the third line to be kept below a limit that is dangerous to the human body in the event of an insulation fault, particularly during charging of the traction battery. Therefore, when designing power converters, an energy budget specified by the design of the vehicle electrical system must be adhered to.

[0008] It has already been proposed to provide a switch in a current path between the capacitors and the third terminal in order to connect the capacitors to the third terminal of the filter device or the reference potential in a first filter mode and to separate them from it in a second filter mode. However, such switches have parasitic capacitances whose magnitude is difficult to control due to manufacturing limitations. In the second filter mode, this leads to a voltage distribution across the capacitors and the switch that is difficult to predict. This significantly complicates the precise determination of the energy budget to ensure electrical safety and, in conjunction with additional filter inductances, may lead to a very imprecisely predictable position of the filter frequencies.

[0009] The invention is based on the object of providing an improved possibility for operating a power converter in an on-board network of an electrically driven vehicle.

[0010] This object is achieved according to the invention in a power converter of the type mentioned at the outset in that the filter device further comprises a third capacitor which is connected between a terminal of the first capacitor facing away from the center node and the first terminal of the filter device, and a fourth capacitor which is connected between a terminal of the second capacitor facing away from the center node and the second terminal of the filter device, wherein in the first filter mode a first current path for an interference current on the first line from the first terminal of the filter device via the third capacitor, a parallel connection of the first capacitor and the second capacitor and the center node to the third terminal of the filter device and a second current path for an interference current on the second line from the second terminal of the filter device via the fourth capacitor,a parallel circuit of the first capacitor and the second capacitor and the center node are formed to the third terminal of the filter device, wherein in the second filter mode an admittance for the interference currents along the first current path and the second current path is at least reduced compared to the first filter mode.

[0011] The power converter according to the invention has a first line for a first potential, a second line for a second potential, and a third line for a reference potential. The power converter further has a filter device. The filter device has a first terminal, a second terminal, and a third terminal. The first terminal is connected to the first line. The second terminal is connected to the second line. The third terminal is connected to the third line. The filter device further has a first capacitor, a second capacitor, a third capacitor, and a fourth capacitor. A center node with an electrically conductive connection to the third terminal is formed between the first capacitor and the second capacitor.The third capacitor is connected between a terminal of the first capacitor facing away from the center node and the first terminal of the filter device. The fourth capacitor is connected between a terminal of the second capacitor facing away from the center node and the second terminal of the filter device. The filter device further comprises a switching device. The switching device is configured to switch between a first filter mode and a second filter mode of the filter device depending on control information. In the first filter mode, a first current path for an interference current on the first line is formed from the first terminal of the filter device via the third capacitor, a parallel circuit of the first capacitor and the second capacitor and the center node to the third terminal of the filter device.In the first filter mode, a second current path for an interference current on the second line is further formed from the second terminal of the filter device via the fourth capacitor, a parallel circuit of the first capacitor and the second capacitor, and the center node to the third terminal of the filter device. In the second filter mode, an admittance for the interference currents along the first current path and the second current path is at least reduced compared to the first filter mode.

[0012] In the power converter according to the invention, the first and second current paths in the first filter mode are routed via a parallel circuit comprising the first capacitor and the second capacitor. This parallel circuit advantageously forms a well-defined capacitance between the third capacitor and the fourth capacitor on the one hand, and the third terminal on the other, which allows precise determination of an energy budget when designing the power converter. With additional advantage, the capacitor network in the first filter mode forms an X-capacitance that enables greater suppression of normal-mode interference. In the second filter mode, the effectively effective Y-capacitances are dominated by the reduction in admittance, essentially by a series circuit of the first capacitor and the third capacitor or by a series circuit of the capacitances of the second capacitor and the fourth capacitor.This enables a significant reduction in the Y capacitances in the second filter mode, which places less strain on the energy budget and allows a more precise determination of your energy budget when designing the power converter compared to conventional filter devices.

[0013] The power converter according to the invention can be designed as an inverter, a DC-DC converter, or an active rectifier. The power converter according to the invention can further comprise a housing in which at least the first line, the second line, the third line, and the filter device are accommodated. The third line can be electrically conductively connected to the housing. The reference potential can therefore also be considered the housing potential.

[0014] Typically, the first potential differs from the second potential. Preferably, the first potential is greater than the second potential. The reference potential is preferably between the first potential and the second potential. The reference potential can also be understood as ground potential. In a preferred embodiment, the first line and the second line are each designed entirely or at least in sections as solid busbars. The first and the second line can be connected to a DC voltage connection of the power converter, on which in particular a connection device for electrically contacting the power converter with a DC voltage source is formed. Preferably, the filter device is arranged on the DC voltage connection side. The interference currents are or contain in particular common-mode currents. The third line is not necessarily designed as a busbar.The third line can be formed by a cable, a ground plane or by a fastening means by which the filter device is fastened in the power converter, in particular to the housing.

[0015] The first capacitor, the second capacitor, the third capacitor, and the fourth capacitor may each have a first terminal and a second terminal, between which the capacitance of the capacitor is provided. The first terminal of the third capacitor may be connected to the first terminal of the filter device. The second terminal of the fourth capacitor may be connected to the second terminal of the filter device.

[0016] The first capacitor, the second capacitor, the third capacitor, and the fourth capacitor can each be formed by a capacitor component or a plurality of interconnected capacitor components. The switching device is preferably a semiconductor switching device, which in particular has one or more transistor structures. Alternatively, it is also possible for the switching device to be an electromechanical switching device, which, for example, has one or more relays.

[0017] Preferably, the filter device of the power converter according to the invention is configured to set a higher pole frequency and / or a lower effective total capacitance for filtering interference currents in the second filter mode between the first terminal and the third terminal, as well as between the second terminal and the third terminal, than in the first filter mode. In the event of a first insulation fault, the discharge time constant resulting from the effective Y-capacitance and a body resistance can thereby be advantageously modified.

[0018] In the power converter according to the invention, in the second filter mode, the admittance along the first current path between the third capacitor and the second capacitor can be at least reduced compared to the first filter mode, and the admittance along the second current path between the fourth capacitor and the first capacitor can be at least reduced compared to the first filter mode.

[0019] However, it is particularly preferred if, in the second filter mode, the first current path in a circuit branch between the third capacitor and the second capacitor and the second current path in a circuit branch between the fourth capacitor and the first capacitor are interrupted.

[0020] As a result, the Y capacitances can be reduced particularly significantly in the second filter mode, since they are smaller than the smallest capacitance of the series circuit as a series connection of the first capacitor and the third capacitor on the one hand, and as a series connection of the second capacitor and the fourth capacitor on the other.

[0021] In particular, in the second filter mode, a capacitance of a circuit branch connecting the first terminal and the center node may correspond to the inverse of the sum of the inverses of the capacitances of the first capacitor and the third capacitor, and a capacitance of a circuit branch connecting the second terminal and the center node may correspond to the inverse of the sum of the inverses of the capacitances of the second capacitor and the fourth capacitor.

[0022] Furthermore, in the first filter mode, a capacitance of a circuit branch connecting the third capacitor and the fourth capacitor on the one hand and the third terminal on the other hand may correspond to the sum of the capacitances of the first capacitor and the second capacitor.

[0023] In a preferred embodiment of the power converter according to the invention, the center node is a common node of the third terminal of the filter device, a terminal of the first capacitor facing away from the third capacitor and / or facing the second capacitor, and a terminal of the second capacitor facing away from the fourth capacitor and / or facing the first capacitor. The terminal of the first capacitor facing away from the third capacitor and / or facing the second capacitor can correspond to the second terminal of the first capacitor. The terminal of the second capacitor facing away from the fourth capacitor and / or facing the first capacitor can correspond to the first terminal of the second capacitor.

[0024] The first terminal of the first capacitor may be connected to the second terminal of the third capacitor. The second terminal of the second capacitor may be connected to the first terminal of the fourth capacitor.

[0025] The center node is preferably connected to the third port of the filter device.

[0026] It is also preferred in the power converter according to the invention if the switching device has a first terminal and a second terminal and a switching path that can be controlled as a function of the control information.

[0027] The first terminal of the switching device can have a common node with the first capacitor and the third capacitor. The second terminal of the third capacitor can be connected to the first terminal of the switching device. The first terminal of the first capacitor can be connected to the first terminal of the switching device.

[0028] Alternatively or additionally, the second terminal of the switching device has a common node with the second capacitor and the fourth capacitor. The second terminal of the second capacitor can be connected to the second terminal of the switching device. The first terminal of the fourth capacitor can be connected to the second terminal of the switching device. In a preferred embodiment, the switching device is configured to switch the switching path conductive to enter the first filter mode and / or to switch it non-conductive to enter the second filter mode.

[0029] With regard to the dimensioning of the capacitances of the power converter according to the invention, it is preferred if the capacitances of the first capacitor and the fourth capacitor are smaller than the capacitances of the second capacitor and the third capacitor, in particular by at least a factor of two, in particular by at least a factor of five. Alternatively, the capacitances of the first capacitor and the fourth capacitor can be larger than the capacitances of the second capacitor and the third capacitor, in particular by at least a factor of two, in particular by at least a factor of five.

[0030] Furthermore, the capacitances of the first capacitor and the fourth capacitor may be equal. Furthermore, the capacitances of the second capacitor and the third capacitor may be equal.

[0031] To enable efficient suppression of differential-mode interference in the second filter mode as well and to compensate for asymmetries at different capacitance values, the filter device can further comprise a fifth capacitor connected in parallel to the first to fourth capacitors at the first terminal and the second terminal of the filter device. In other words, the fifth capacitor can provide a fixed X-capacitance. In particular, the fifth capacitor has a capacitance that is at least five times, preferably ten times, greater than the largest capacitance of the first to fourth capacitors.

[0032] In the power converter according to the invention, it can further be provided that a fourth terminal of the filter device is the first terminal of the filter device or is connected to the first line, a fifth terminal of the filter device is the second terminal of the filter device or is connected to the second line and a sixth terminal of the filter device is the third terminal of the filter device or is connected to the third line.In a preferred development, it can be provided that the filter device further comprises a sixth capacitor and a seventh capacitor, between which a second center node with an electrically conductive connection to the sixth terminal is formed, an eighth capacitor which is connected between a terminal of the sixth capacitor facing away from the second center node and the fourth terminal of the filter device, a ninth capacitor which is connected between a terminal of the seventh capacitor facing away from the second center node and the fifth terminal of the filter device, and a second switching device which is configured to switch between the first filter mode and the second filter mode of the filter device depending on the control information.Furthermore, it can be provided that a third current path for the interference current on the first line from the fourth terminal of the filter device via the eighth capacitor, a parallel circuit of the sixth capacitor and the seventh capacitor, and the second center node to the sixth terminal of the filter device, and a fourth current path for the interference current on the second line from the fifth terminal of the filter device via the ninth capacitor, a parallel circuit of the sixth capacitor and the seventh capacitor, and the second center node to the sixth terminal of the filter device are formed. In the second filter mode, an admittance for the interference currents along the third current path and the fourth current path can be at least reduced compared to the first filter mode.By providing the sixth to ninth capacitors, i.e. a second group of four capacitors connected in parallel to the first to fourth capacitors, a further symmetrization of the current distribution within the filter device can be achieved.

[0033] In a preferred embodiment, it can be provided that the capacitances of the sixth capacitor and the ninth capacitor are larger, in particular by at least a factor of two, in particular by at least a factor of five, than the capacitances of the seventh capacitor and the eighth capacitor if the capacitances of the first capacitor and the fourth capacitor are smaller than the capacitances of the second capacitor and the third capacitor. Alternatively, it can be provided that the capacitances of the sixth capacitor and the ninth capacitor are smaller, in particular by at least a factor of two, in particular by at least a factor of five, than the capacitances of the seventh capacitor and the eighth capacitor if the capacitances of the first capacitor and the fourth capacitor are larger than the capacitances of the second capacitor and the third capacitor.The capacitance ratios in the second group can therefore be reversed relative to the first group comprising the first to fourth capacitors. In particular, the capacitances of the first, fourth, seventh, and eighth capacitors can be identical, and / or the capacitances of the second, third, sixth, and ninth capacitors can be identical.

[0034] Furthermore, all statements regarding the first to fourth capacitors can be applied to the sixth to ninth capacitors, and all statements regarding the first switching device can be applied to the second switching device. Thus, in particular, the following applies:

[0035] The sixth capacitor, the seventh capacitor, the eighth capacitor, and the ninth capacitor may each have a first terminal and a second terminal, between which the capacitance of the capacitor is provided. The first terminal of the eighth capacitor may be connected to the fourth terminal of the filter device. The second terminal of the ninth capacitor may be connected to the fifth terminal of the filter device.

[0036] The sixth capacitor, the seventh capacitor, the eighth capacitor, and the ninth capacitor can each be formed by a capacitor component or a plurality of interconnected capacitor components. The second switching device is preferably a semiconductor switching device, which in particular has one or more transistor structures. Alternatively, it is also possible for the second switching device to be an electromechanical switching device, which, for example, has one or more relays.

[0037] Preferably, the filter device is configured to set a higher pole frequency and / or a lower effective total capacitance for filtering the interference currents in the second filter mode between the fourth terminal and the sixth terminal and between the fifth terminal and the sixth terminal than in the first filter mode.

[0038] In the second filter mode, the admittance along the third current path between the eighth capacitor and the seventh capacitor can be at least reduced compared to the first filter mode, and the admittance along the fourth current path between the ninth capacitor and the sixth capacitor can be at least reduced compared to the first filter mode.

[0039] However, it is particularly preferred if, in the second filter mode, the third current path in a circuit branch between the eighth capacitor and the seventh capacitor and the fourth current path in a circuit branch between the ninth capacitor and the sixth capacitor are interrupted.

[0040] In particular, in the second filter mode, a capacitance of a circuit branch connecting the fourth terminal and the second center node may correspond to the inverse of the sum of the inverses of the capacitances of the sixth capacitor and the eighth capacitor, and a capacitance of a circuit branch connecting the fifth terminal and the second center node may correspond to the inverse of the sum of the inverses of the capacitances of the seventh capacitor and the ninth capacitor.

[0041] Furthermore, in the first filter mode, a capacitance of a circuit branch connecting the eighth capacitor and the ninth capacitor on the one hand and the sixth terminal on the other hand may correspond to the sum of the capacitances of the sixth capacitor and the seventh capacitor.

[0042] In a preferred embodiment, the second center node is a common node of the sixth terminal of the filter device, a terminal of the sixth capacitor facing away from the eighth capacitor and / or facing the seventh capacitor, and a terminal of the seventh capacitor facing away from the ninth capacitor and / or facing the sixth capacitor. The terminal of the sixth capacitor facing away from the eighth capacitor and / or facing the seventh capacitor can correspond to the second terminal of the sixth capacitor. The terminal of the seventh capacitor facing away from the ninth capacitor and / or facing the sixth capacitor can correspond to the first terminal of the seventh capacitor.

[0043] The first terminal of the sixth capacitor may be connected to the second terminal of the eighth capacitor. The second terminal of the seventh capacitor may be connected to the first terminal of the ninth capacitor.

[0044] The second center node is preferably connected to the sixth port of the filter device.

[0045] The second switching device can have a first terminal and a second terminal and a switching path that can be controlled as a function of the control information.

[0046] The first terminal of the second switching device can have a common node with the sixth capacitor and the eighth capacitor. The second terminal of the eighth capacitor can be connected to the first terminal of the second switching device. The first terminal of the sixth capacitor can be connected to the first terminal of the second switching device.

[0047] Alternatively or additionally, the second terminal of the second switching device has a common node with the seventh capacitor and the ninth capacitor. The second terminal of the seventh capacitor can be connected to the second terminal of the second switching device. The first terminal of the ninth capacitor can be connected to the second terminal of the second switching device.

[0048] In a preferred embodiment, the second switching device is configured to switch the switching path conductive to assume the first filter mode and / or to switch it blocking to assume the second filter mode.

[0049] In a preferred embodiment of the power converter according to the invention, the filter device comprises a circuit board. The first to fourth capacitors can be arranged on the circuit board. The fifth capacitor can also be arranged on the circuit board. The sixth to ninth capacitors can also be arranged on the circuit board. The first to third terminals of the filter device can be arranged on the circuit board. The first switching device can be arranged on the circuit board. The second switching device can also be arranged on the circuit board.

[0050] The power converter according to the invention can further comprise an intermediate circuit capacitor connected between the first line and the second line. The intermediate circuit capacitor can have a capacitance that is at least one hundred times, preferably five hundred times, greater than the largest capacitance of the first to fourth capacitors. The capacitance of the intermediate circuit capacitor is typically, in particular, at least ten times, preferably at least fifty times, greater than the capacitance of the fifth capacitor. The power converter according to the invention can further comprise a converter circuit connected between the first line and the second line. The converter circuit can comprise power semiconductor switches, which are connected in particular as a switching cell, power bridge, or B6 bridge circuit, in order to convert the voltage present between the first line and the second line in a switching operation.Preferably, the filter device is arranged on the side of the intermediate circuit capacitor facing away from the converter circuit.

[0051] The power converter according to the invention can further comprise inductive filter elements that act as series inductors in the first line and the second line and are arranged on the intermediate circuit capacitor side and / or the DC voltage input side, in particular spatially close to the filter device. The filter elements can be formed by ferrite cores, for example nanocrystalline cores, iron powder cores, or other cores made of magnetic material, around the lines.

[0052] Preferably, parasitic inductances along the first line and the second lines between the DC voltage connection on the one hand and the first connection and the second connection of the filter device or the DC voltage connection-side filter elements on the other hand are lower than parasitic inductances between the first connection and the second connection of the filter device or the intermediate circuit capacitor-side filter elements on the one hand and the intermediate circuit capacitor on the other hand.

[0053] The object underlying the invention is further achieved by an on-board electrical system for an electrically driven vehicle, comprising at least one previously described power converter, a traction battery, a charging device which can be connected to an electrical network external to the vehicle for charging or discharging the traction battery, and a control device which is configured to provide the control information for adopting the second filter mode if and / or as long as the charging device is connected to the electrical network external to the vehicle.

[0054] Thus, the filter mode can advantageously be specified in a ferry operation of the vehicle or the on-board network and the second filter mode can be specified in a charging operation.

[0055] The traction battery preferably has a nominal voltage of at least 400 volts, preferably at least 600 volts, particularly preferably at least 800 volts.

[0056] A power converter of the vehicle electrical system can be designed as an inverter which is designed to electrically supply an electrical machine, in particular a permanent or electrically excited synchronous machine, an axial flux motor or an asynchronous machine, with a multi-phase alternating voltage for driving the vehicle.

[0057] A power converter of the on-board electrical system can form part of the charging device and be designed to convert a direct or alternating voltage provided by the vehicle-external electrical network into a direct voltage for charging the traction battery.

[0058] A power converter of the vehicle electrical system can be designed as a DC-DC converter, which is configured to couple the vehicle electrical system to another vehicle electrical system, in particular a low-voltage vehicle electrical system. A potential of the low-voltage vehicle electrical system can correspond to the reference potential.

[0059] The vehicle electrical system may further comprise an electrical line, for example, an electrically conductive attachment or a ground strap, by means of which the third line of the at least one power converter is electrically connected to a body of the vehicle. Further advantages and details of the present invention will become apparent from the exemplary embodiments described below and from the drawings. These are schematic representations and show:

[0060] Fig. 1 is a circuit diagram of an embodiment of the power converter according to the invention;

[0061] Fig. 2 is an equivalent circuit diagram of the filter device in the first filter mode according to the embodiment;

[0062] Fig. 3 is an equivalent circuit diagram of the filter device in the second filter mode according to the embodiment;

[0063] Fig. 4 is a schematic diagram of the power converter according to the embodiment;

[0064] Fig. 5 is a circuit diagram of the filter device according to a second embodiment of the power converter according to the invention;

[0065] Fig. 6 is a circuit diagram of the filter device according to a third embodiment of the power converter according to the invention; and

[0066] Fig. 7 is a block diagram of an embodiment of the on-board network according to the invention in a vehicle.

[0067] Fig. 1 is a circuit diagram of an embodiment of a power converter 1 .

[0068] The power converter 1 has a first line 2 for a first potential 3, a second line 4 for a second potential 5, and a third line 6 for a reference potential 7, which can also be considered ground potential. For example, the first potential 3 is higher than the second potential 5, and the power converter 1 is configured to operate with a potential difference of 800 volts between the first potential 3 and the second potential 5. The reference potential 7 is located, for example, between the first potential 3 and the second potential 5.

[0069] The power converter 1 further comprises a filter device 8. Specifically, the filter device 8 serves as an interference suppression filter, i.e., to improve the electromagnetic compatibility of the power converter 1, and is preferably arranged close to a DC voltage terminal 9.

[0070] The filter device 8 has a first connection 10 connected to the first line 2, a second connection 11 connected to the second line 4, and a third connection 12 connected to the third line 6. Furthermore, the filter device has a first capacitor 13 and a second capacitor 14, between which a center node 15 is formed with an electrically conductive connection to the third connection 12. The filter device 8 further has a third capacitor 16 and a fourth capacitor 17. First connections of the capacitors 13, 14, 16, 17 are provided with the reference numerals 13a, 14a, 16a, 17a, and second connections of the capacitors 13, 14, 16, 17 are provided with the reference numerals 13b, 14b, 16b, 17b.

[0071] The third capacitor 16 is connected between the first terminal 13a, which faces away from the center node 15, of the first capacitor 13 and the first terminal 10 of the filter device 8. The fourth capacitor 17 is connected between the second terminal 14b, which faces away from the center node 15, of the second capacitor 14 and the second terminal 11 of the filter device 8.

[0072] In addition, the filter device 8 has a switching device 19. The switching device 19 is configured to switch between a first filter mode and a second filter mode depending on control information 20. In the first filter mode, a first current path 21 for an interference current on the first line 2 is formed from the first terminal 10, the third capacitor 16, a parallel connection of the first capacitor 13 and the second capacitor 14 and the center node 15 to the third terminal 12. In the first filter mode, a second current path 22 for an interference current is formed on the second line 4 from the second terminal 11 via the fourth capacitor 17, the parallel connection of the first capacitor 13 and the second capacitor 14 and the center node 15 to the third terminal 12.In the second filter mode, the admittance for the interference currents along the first current path 21 and the second current path 22 is reduced compared to the first filter mode. The current paths 21, 22 are illustrated purely schematically in Fig. 1 by differently dashed lines.

[0073] According to the present embodiment, the current paths 21, 22 are each partially interrupted in the second filter mode. The interruption of the first current path 21 is in a circuit branch between the third capacitor

[0074] 16 and the second capacitor 14. The interruption of the second current path 22 is provided in a circuit branch between the fourth capacitor

[0075] 17 and the first capacitor 13.

[0076] Fig. 2 and Fig. 3 are each an equivalent circuit diagram of the filter device 8, wherein Fig. 2 shows the first filter mode and Fig. 3 the second filter mode.

[0077] In the first filter mode, the first capacitor 13 and the second capacitor 14 are connected in parallel, so that the capacitance Ci of the first capacitor 13 and the capacitance C2 of the second capacitor 14 add up to a total capacitance between a circuit node 23, which in the equivalent circuit diagram lies between the third capacitor 16 and the fourth capacitor 17, and the center node 15. The capacitance C3 of the third capacitor 16 acts in a circuit branch 24 between the circuit node 23 and the first terminal 10 of the filter device 8. The capacitance C4 of the fourth capacitor 17 acts in a circuit branch 25 between the circuit node 23 and the second terminal 11 of the filter device 8. The capacitor network thus formed in the first filter mode provides both a Y capacitance for filtering common-mode interference and an X capacitance for filtering differential-mode interference.In the second filter mode, the first capacitor is 13 and the third capacitor.

[0078] 16 are connected in series in a circuit branch 26 between the first terminal 10 of the filter device 8 and the center node 15. Accordingly, in the second filter mode, the second capacitor 14 and the fourth capacitor

[0079] 17 are connected in series in a circuit branch 27 between the second terminal 11 of the filter device 8 and the center node 15. In the second filter mode, Y-capacitances act in the circuit branches 26, 27, whereby the Y-capacitance in circuit branch 26 is the inverse of the sum of the inverses of C1 and C2, and in circuit branch 27 is the inverse of the sum of the inverses of C2 and C4. Thus, the Y-capacitance in each of the circuit branches 26, 27 is lower than the lowest capacitance in the corresponding circuit branch 26, 27.

[0080] Referring again to Fig. 1, the filter device 8 is implemented in terms of circuitry in the present exemplary embodiment in particular in that the center node 15 is a common node of the third terminal 12 of the filter device 8, the second terminal 13b of the first capacitor 13, which is remote from the third capacitor 16 and faces the second capacitor 14, and the first terminal 14a of the second capacitor 14, which is remote from the fourth capacitor 17 and faces the first capacitor 13. The center node 15 is connected to the third terminal 12 of the filter device 8.

[0081] The switching device 19 has a first terminal 19a, a second terminal 19b, and a switching path formed between the terminals 19a, 19b and controllable as a function of the control information 20. The first terminal 19a of the switching device 19 has a common node with the first capacitor 13 and the third capacitor 16. The first terminal 19a of the switching device 19 is connected to the first terminal 13a of the first capacitor 13 and to the second terminal 16b of the third capacitor 16. The second terminal 19b of the switching device 19 has a common node with the second capacitor 14 and the fourth capacitor 17. The second terminal 19b of the switching device 19 is connected to the second terminal 14b of the second capacitor 14 and to the first terminal 17a of the fourth capacitor 17.The switching device 19 is designed to switch the switching path conductive to assume the first filter mode and to switch it blocking to assume the second filter mode.

[0082] In the present exemplary embodiment, the first terminal 16a of the third capacitor 16 is also connected to the first terminal 10 of the filter device 8. The second terminal 16b of the third capacitor 16 is connected to the first terminal 13a of the first capacitor 13. The second terminal 13b of the first capacitor 13 is connected to the first terminal 14a of the second capacitor and to the third terminal 12 of the filter device 8. The first terminal 14a of the second capacitor 14 is connected to the second terminal 13b of the first capacitor 13 and to the third terminal 12 of the filter device 8. The second terminal 14b of the second capacitor 14 is connected to the first terminal 17a of the fourth capacitor 17. The second terminal 17b of the fourth capacitor 17 is connected to the second terminal 11 of the filter device 8.

[0083] According to the present exemplary embodiment, a fifth capacitor 28 with a first terminal 28a and a second terminal 28b is further provided. The fifth capacitor 28 is connected in parallel with the first to fourth capacitors 13, 14, 16, 17 to the first terminal 10 of the filter device 8 and to the second terminal 11 of the filter device 8. The first terminal 10 of the filter device 8, the first terminal 16a of the third capacitor 16, and the first terminal 28a of the fifth capacitor 28 form a common circuit node. Furthermore, the second terminal 11 of the filter device 8, the second terminal 17b of the fourth capacitor 17, and the second terminal 28b of the fifth capacitor 28 form a common circuit node. The fifth capacitor 28 provides a fixed X-capacitance.

[0084] In the present exemplary embodiment, the capacitances Ci and C4 are identical and smaller than the capacitances C2 and C3, which are themselves identical. The capacitance Cs of the fifth capacitor 28 is in turn larger than the capacitances C2 and C3. Example values ​​of the capacitances are Ci = C4 = 20 nF, C2 = C3 = 100 nF, C5 = 1 pF. According to an alternative exemplary embodiment, the capacitances Ci and C4 are identical and larger than the capacitances C2 and C3, which are themselves identical. For example, Ci = C4 = 100 nF, C2 = C3 = 20 nF, C5 = 1 pF.

[0085] Fig. 1 further shows an intermediate circuit capacitor 40, which is connected between the first line 2 and the second line 4 and whose capacitance is at least 50 pF, and a converter circuit 41, which is connected between the first line 2 and the second line 4. The filter device 8 is clearly arranged on the side of the intermediate circuit capacitor 40 facing away from the converter circuit 41.

[0086] The power converter 1 further comprises four inductive filter elements 42, 43, 44, 45, which act as series inductances in the lines 2, 4 and are formed, for example, by ferrite cores, such as nanocrystalline cores, iron powder cores, or other cores made of magnetic material, around the lines 2, 4. The filter elements 42 to 45 are arranged close to the filter device 8. The filter elements 42, 44 are arranged on the DC voltage input side with respect to the filter device 8. The filter elements 43, 45 are arranged on the intermediate circuit capacitor side with respect to the filter device 8.

[0087] In addition, parasitic inductances Li are shown schematically in Fig. 1 P , Lin along the first line 2 or the second line 4 between the DC voltage connection 9 and the filter device 8 or the filter elements 42, 44 as well as parasitic inductances L2 P, L2n along the first line 2 or the second line 4 between the filter device 8 or the filter elements 43, 45 and the intermediate circuit capacitor 40. The arrangement of the filter device 8 is preferably selected such that Li P and Lin less than L2 P and L2n to enable the most efficient filtering possible.

[0088] Fig. 4 is a schematic diagram of the power converter 1 according to the exemplary embodiment. The filter device 8 has a printed circuit board 50 on which the terminals 10, 11, 12, the capacitors 13, 14, 16, 17, 28, and the switching device 19 are arranged. The first line 2 and the second line 4 are each formed by solid busbars 51, 52, which are contacted with the terminals 10, 11 on the printed circuit board 50. The DC voltage terminal 9, designed as a connection device 53, is connected to a first end of the busbars 51, 52. The converter circuit 41 is connected to a second end of the busbars 51, 52. The intermediate circuit capacitor 40 is also in contact with the busbars 51, 52 and, relative to the length of the busbars 51, is located closer to the converter circuit 41 than to the filter device 8.

[0089] The third terminal 12 of the filter device 8 is not connected to the busbars 51, 52, but is connected to a housing 55 of the power converter 1 by means of a fastening means 54, which forms the third line 6. The reference potential 7 can therefore also be considered the housing potential. The lines 2, 4 or the busbars 51, 52, the filter device 8, the intermediate circuit capacitor 40, and the converter circuit 41 are housed in the housing 55.

[0090] The power converter 1 can be designed as an inverter, a DC-DC converter, or an active rectifier. The converter circuit 41 comprises suitable semiconductor switching elements for this purpose.

[0091] Fig. 5 is a circuit diagram of the filter device 8 according to a second embodiment of the power converter 1. All information about the first embodiment can be applied analogously to the second embodiment, unless otherwise described below. Identical or equivalent components are provided with identical reference numerals. According to the second embodiment, the filter device 8 additionally has a sixth capacitor 63 and a seventh capacitor 64, between which a second center node 65 with an electrically conductive connection to the third terminal 12 is formed. The filter device 8 further has an eighth capacitor 66 and a ninth capacitor 67. First terminals of the capacitors 63, 64, 66, 67 are provided with the reference numerals 63a, 64a, 66a, 67a and second terminals of the capacitors 63, 64, 66, 67 are provided with the reference numerals 63b, 64b, 66b, 67b.

[0092] The eighth capacitor 66 is connected between the first terminal 63a, which faces away from the second center node 65, of the sixth capacitor 63 and the first terminal 10 of the filter device 8. The ninth capacitor 67 is connected between the second terminal 64b, which faces away from the second center node 65, of the seventh capacitor 64 and the second terminal 11 of the filter device 8.

[0093] In addition, the filter device 8 has a second switching device 69. The second switching device 69 is configured to switch between the first filter mode and the second filter mode depending on the control information 20. In the first filter mode, a third current path 71 is formed for the interference current on the first line 2 from the first terminal 10, the eighth capacitor 66, a parallel connection of the sixth capacitor 63 and the seventh capacitor 64, and the second center node 65 to the third terminal 12. In the first filter mode, a fourth current path 72 is further formed for the interference current on the second line 4 from the second terminal 11 via the ninth capacitor 67, the parallel connection of the sixth capacitor 63 and the seventh capacitor 64, and the second center node 65 to the third terminal 12.In the second filter mode, an admittance for the interference currents along the third current path 71 and the fourth current path 72 is reduced compared to the first filter mode. The current paths 21, 22, 71, 72 are again illustrated purely schematically by dashed lines in Fig. 5. According to the second exemplary embodiment, the current paths 71, 72 are each partially interrupted in the second filter mode. The interruption of the third current path 71 is provided in a circuit branch between the eighth capacitor 66 and the seventh capacitor 64. The interruption of the fourth current path 72 is provided in a circuit branch between the ninth capacitor 67 and the sixth capacitor 63.

[0094] In the first filter mode, the sixth capacitor 63 and the seventh capacitor 64 are connected in parallel, so that the capacitance Ce of the sixth capacitor 63 and the capacitance C? of the seventh capacitor 64 add up to a total capacitance between a circuit node, which, analogous to circuit node 23 in the equivalent circuit diagram according to Fig. 2, lies between the eighth capacitor 66 and the ninth capacitor 67, and the second center node 65. In a circuit branch corresponding to circuit branch 24 according to Fig. 2, between the circuit node corresponding to circuit node 23 and the first terminal 10 of the filter device 8, the capacitance Cs of the eighth capacitor 66 acts. In a circuit branch corresponding to circuit branch 25 according to Fig. 2, between the circuit node corresponding to circuit node 23 and the second terminal 11 of the filter device 8, the capacitance C9 of the ninth capacitor 67 acts.The capacitor network formed in the first filter mode from the sixth to ninth capacitors 63, 64, 66, 67 provides both a Y capacitance for filtering common-mode interference and an X capacitance for filtering differential-mode interference.

[0095] In the second filter mode, the sixth capacitor 63 and the eighth capacitor 66 are connected in series in a circuit branch 76 between the first terminal 10 of the filter device 8 and the second center node 65. Accordingly, in the second filter mode, the seventh capacitor 64 and the ninth capacitor 67 are also connected in series in a circuit branch 77 between the second terminal 11 of the filter device 8 and the second center node 65. In the second filter mode, Y-capacitances act in the circuit branches 76, 77, with the Y-capacitance in circuit branch 76 being the inverse of the sum of the inverses of C and C, and in circuit branch 77 being the inverse of the sum of the inverses of C and C. Thus, the Y-capacitance in each of the circuit branches 76, 77 is less than the smallest capacitance in the corresponding circuit branch 76, 77.

[0096] The second center node 65 is a common node of the third terminal 12 of the filter device 8, the second terminal 63b of the sixth capacitor 63 facing away from the eighth capacitor 66 and facing the seventh capacitor 64, and the first terminal 64a of the seventh capacitor 64 facing away from the ninth capacitor 67 and facing the sixth capacitor 63. The second center node 65 is connected to the third terminal 12 of the filter device 8.

[0097] The second switching device 69 has a first terminal 69a, a second terminal 69b, and a switching path formed between the terminals 69a, 69b and controllable as a function of the control information 20. The first terminal 69a of the switching device 69 has a common node with the sixth capacitor 63 and the eighth capacitor 66. The first terminal 69a of the second switching device 69 is connected to the first terminal 63a of the sixth capacitor 63 and to the second terminal 66b of the eighth capacitor 66. The second terminal 69b of the second switching device 69 has a common node with the seventh capacitor 64 and the ninth capacitor 67. The second terminal 69b of the second switching device 69 is connected to the second terminal 64b of the seventh capacitor 64 and to the first terminal 67a of the ninth capacitor 67.The second switching device 69 is configured to switch the switching path conductive to assume the first filter mode and to switch it blocking to assume the second filter mode.

[0098] The first terminal 66a of the eighth capacitor 66 is connected to the first terminal

[0099] 10 of the filter device 8. The second terminal 66b of the eighth capacitor 66 is connected to the first terminal 53a of the sixth capacitor 63. The second terminal 63b of the sixth capacitor 63 is connected to the first terminal 64a of the seventh capacitor 64 and to the third terminal 12 of the filter device 8. The first terminal 64a of the seventh capacitor 64 is connected to the second terminal 63b of the sixth capacitor 63 and to the third terminal 12 of the filter device 8. The second terminal 64b of the seventh capacitor 64 is connected to the first terminal 67a of the ninth capacitor 67. The second terminal 67b of the ninth capacitor 67 is connected to the second terminal 11 of the filter device 8.

[0100] In the present embodiment, the capacitances Ce and C9 are identical, and the capacitances C7 and Cs are identical. If the capacitances Ci, C4 are larger than the capacitances C2, C3, the capacitances Ce, C9 are smaller than the capacitances C7, Cs. If the capacitances Ci, C4 are smaller than the capacitances C2, C3, the capacitances Ce, C9 are larger than the capacitances C7, Cs. In particular, the capacitances Ci, C4, C7, and Cs are identical, and the capacitances C2, C3, Ce, C9 are identical.

[0101] In the second embodiment, the sixth to ninth capacitors 63, 64, 66, 67 and the second switching device 69 are also arranged on the circuit board 50 (see Fig. 4).

[0102] Fig. 6 is a circuit diagram of the filter device 8 according to a third embodiment of the power converter 1, which corresponds to the second embodiment except for the following deviations.

[0103] According to the third exemplary embodiment, the filter device 8 additionally has a fourth terminal 60 connected to the first line 2, a fifth terminal 61 connected to the second line 4, and a sixth terminal 62 connected to the third line 6. In this case, the following is provided: The second center node 65 has an electrically conductive connection to the sixth terminal 12 of the filter device 8. The eighth capacitor 66 is connected between the first terminal 63a of the sixth capacitor 63 and the fourth terminal 60 of the filter device 8. The ninth capacitor 67 is connected between the second terminal 64b of the seventh capacitor 64 and the fifth terminal 61 of the filter device 8.The third current path 71 runs from the fourth terminal 60 via the eighth capacitor 66, the parallel connection of the sixth capacitor 63 and the seventh capacitor 64, and the second center node 65 to the sixth terminal 62. The fourth current path 72 runs from the fifth terminal 61 via the ninth capacitor 67, the parallel connection of the sixth capacitor 63 and the seventh capacitor 64, and the second center node 65 to the sixth terminal 62.

[0104] In the first filter mode, the capacitance Cs acts in a circuit branch corresponding to the circuit branch 24 according to Fig. 2, between the circuit node corresponding to the circuit node 23 and the fourth terminal 60. The capacitance C9 acts in a circuit branch corresponding to the circuit branch 25 according to Fig. 2, between the circuit node corresponding to the circuit node 23 and the fifth terminal 61. In the second filter mode, the sixth capacitor 63 and the eighth capacitor 66 are connected in series in a circuit branch 76 between the fourth terminal 10 and the second center node 65, and the seventh capacitor 64 and the ninth capacitor 67 are connected in series in a circuit branch 77 between the fifth terminal 61 and the second center node 65.

[0105] The second center node 65 is a common node of the sixth terminal 62, the second terminal 63b of the sixth capacitor 63, and the first terminal 64a of the seventh capacitor 64. The second center node 65 is connected to the sixth terminal 62.

[0106] The first terminal 66a of the eighth capacitor 66 is connected to the fourth terminal 60 of the filter device 8. The second terminal 66b of the eighth capacitor 66 is connected to the first terminal 63a of the sixth capacitor 63. The second terminal 63b of the sixth capacitor 63 is connected to the first terminal 64a of the seventh capacitor 64 and to the sixth terminal 62. The first terminal 64a of the seventh capacitor 64 is connected to the second terminal 63b of the sixth capacitor 63 and to the sixth terminal 62. The second terminal 64b of the seventh capacitor 64 is connected to the first terminal 67a of the ninth capacitor 67. The second terminal 67b of the ninth capacitor 67 is connected to the fifth terminal 61.

[0107] In the third embodiment, all capacitors 13, 14, 16, 17, 28, 63, 64, 66, 67 and the switching devices 19, 69, along with the terminals 10, 11, 12, 60, 61, 62, can be arranged on the circuit board 50 (see Fig. 4). Alternatively, it is also possible for the sixth to ninth capacitors 63, 64, 66, 67, the second switching device 69, and the fourth to sixth terminals 60, 61, 62 to be arranged on an additional circuit board (not shown).

[0108] Furthermore, the second and third exemplary embodiments can also be combined in such a way that only some of the connections 60, 61, 62 are designed as separate connections and some of the connections are identical to the connections 10, 11, 12. Thus, the fourth connection 60 can be identical to the first connection 10 and the fifth connection 61 can be identical to the second connection 11, and the sixth connection 62 can be provided in addition to the third connection 12. The fourth connection 60 and the fifth connection 61 can also be provided in addition to the first connection 10 and the second connection 12, and the third and sixth connections 12, 62 can be identical.

[0109] Fig. 7 is a block diagram of an embodiment of an on-board network 101 in a vehicle 100.

[0110] The on-board electrical system 101 includes a traction battery 102 with a nominal voltage of, for example, 800 volts, a charging device 103 that can be connected to an external electrical network 104 for charging or discharging the traction battery 102, and a control device 105 configured to provide the control information 20. The on-board electrical system 101 can be considered a high-voltage electrical system because its operating voltage is regularly above 60 V.

[0111] The vehicle electrical system 101 includes a power converter 1 according to one of the previously described exemplary embodiments, which is designed as an inverter. The power converter 1 is configured to electrically supply an electric machine 106 of the vehicle electrical system 101 with a multiphase alternating voltage for driving the vehicle 100. The electric machine 106 is, for example, a permanently or electrically excited synchronous machine, an axial flux machine, or an asynchronous machine.

[0112] The vehicle electrical system 101 has a further power converter 1a according to the previously described embodiment, which is designed as an active rectifier or as a DC-DC converter and forms part of the charging device 103. The power converter 1a is configured to convert a DC or AC voltage provided by the vehicle-external electrical network 104 into a DC voltage for charging the traction battery 102.

[0113] The vehicle electrical system 101 has a further power converter 1b according to the previously described embodiment, which is designed as a DC-DC converter. The power converter 1b is configured to couple the vehicle electrical system 101 to a further vehicle electrical system 107 of the vehicle 100. The further vehicle electrical system 107 is, for example, a low-voltage vehicle electrical system with an operating voltage of less than 60 volts, for example, 12 volts, 24 volts, or 48 volts.

[0114] The control device 105 communicates with the charging device 103 via a signal line symbolized by a double arrow. The control device 105 is configured to provide the power converters 1, 1a, 1b with the control information 20 for entering the second filter mode if and as long as the charging device 103 is connected to the vehicle-external electrical network 104. The second filter mode can therefore be understood in particular as a charging mode.

[0115] The control information 20, however, is provided in particular for entering the first filter mode when the charging device 103 is disconnected from the vehicle-external electrical network 104 and when the vehicle 100 is moving. The first filter mode can therefore also be considered a driving mode.

[0116] The vehicle electrical system 101 can further comprise electrical conductors by means of which the third line 6 (see Fig. 1) of a respective power converter 1, 1a, 1b is electrically connected to a body 108 of the vehicle 101, so that the reference potential 7 can also be considered a body potential. This is simultaneously one of the potentials of the further vehicle electrical system 107.

[0117] The vehicle 100 can accordingly be designed as a battery electric vehicle (BEV) or as a hybrid vehicle.

Claims

Patent claims 1 . Power converter (1, 1 a, 1 b) for an on-board network (101) of an electrically driven vehicle (100), comprising a first line (2) for a first potential (3), a second line (4) for a second potential (5), a third line (6) for a reference potential (7) and a filter device (8), which - a first terminal (10) connected to the first line (2), - a second terminal (11) connected to the second line (4), - a third terminal (12) connected to the third line (6), - a first capacitor (13) and a second capacitor (14), between which a central node (15) is formed with an electrically conductive connection to the third terminal (12), and - a switching device (19) which is designed to switch between a first filter mode and a second filter mode of the filter device (8) as a function of control information (20), characterized in that the filter device (8) further comprises - a third capacitor (16) connected between a terminal (13a) of the first capacitor (13) facing away from the central node (15) and the first terminal (10) of the filter device (8), and - a fourth capacitor (17) which is connected between a terminal (14b) of the second capacitor (14) facing away from the central node (15) and the second terminal (11) of the filter device (8), wherein in the first filter mode - a first current path (21) for a disturbance current on the first line (2) from the first terminal (10) of the filter device (8) via the third capacitor (16), a parallel circuit of the first capacitor (13) and the second capacitor (14) and the center node (15) to the third terminal (12) of the filter device (8) and - a second current path (22) for an interference current on the second line from the second terminal (11) of the filter device (8) via the fourth capacitor (17), a parallel circuit of the first capacitor (13) and the second capacitor (14) and the center node (15) to the third terminal (12) of the filter device (8) are formed, wherein in the second filter mode an admittance for the interference currents along the first current path (21) and the second current path (22) is at least reduced compared to the first filter mode.

2. Power converter according to claim 1, wherein the filter device (8) is designed to set a higher pole frequency and / or a lower effective total capacitance for filtering the interference currents in the second filter mode between the first terminal (10) and the third terminal (12) and between the second terminal (11) and the third terminal (12) than in the first filter mode.

3. Power converter according to claim 1 or 2, wherein in the second filter mode - the admittance along the first current path (21) between the third capacitor (16) and the second capacitor (14) is at least reduced compared to the first filter mode and the admittance along the second current path (22) between the fourth capacitor (17) and the first capacitor (13) is at least reduced compared to the first filter mode or - the first current path (21) in a circuit branch between the third capacitor (16) and the second capacitor (14) and the second current path (22) in a circuit branch between the fourth capacitor (17) and the first capacitor (13) are interrupted.

4. Power converter according to one of the preceding claims, wherein the center node (15) is a common node - the third connection (12) of the filter device (8), - a terminal (13b) of the first capacitor (13) facing away from the third capacitor (16) and / or facing the second capacitor (14) and - a terminal (14a) of the second capacitor (14) facing away from the fourth capacitor (17) and / or facing the first capacitor (13).

5. Power converter according to one of the preceding claims, wherein the center node (15) is connected to the third terminal (12) of the filter device (8).

6. Power converter according to one of the preceding claims, wherein the switching device (19) has a first terminal (19a) and a second terminal (19b) and a switching path which can be controlled as a function of the control information (20).

7. Power converter according to claim 6, wherein the first terminal (19a) of the switching device (19) has a common node with the first capacitor (13) and the third capacitor (16) and / or the second terminal (19b) of the switching device (19) has a common node with the second capacitor (14) and the fourth capacitor (17).

8. Power converter according to claim 6 or 7, wherein the switching device (19) is configured to switch the switching path conductive to assume the first filter mode and / or to switch it blocking to assume the second filter mode.

9. Power converter according to one of the preceding claims, wherein the capacitances (Ci, C4) of the first capacitor (13) and the fourth capacitor (17), in particular at least by a factor of two, in particular at least by a factor of five, smaller or larger than the capacitances (C2, C3) of the second capacitor (14) and the third capacitor (16).

10. Power converter according to one of the preceding claims, wherein the capacitances (Ci, C4) of the first capacitor (13) and the fourth capacitor (17) are equal and / or the capacitances (C2, C3) of the second capacitor (14) and the third capacitor (16) are equal. 11 . Power converter according to one of the preceding claims, wherein the filter device (8) further comprises a fifth capacitor (28) which is connected in parallel to the first to fourth capacitors (13, 14, 16, 17) to the first terminal (10) and to the second terminal (11) of the filter device (8) and in particular has a capacitance (Cs) which is at least five times greater, preferably ten times greater, than the largest capacitance (Ci, C2, C3, C4) of the first to fourth capacitors (13, 14, 16, 17).

12. Power converter according to one of the preceding claims, wherein a fourth terminal (60) of the filter device (8) is the first terminal (10) of the filter device or is connected to the first line (2), wherein a fifth terminal (61) of the filter device (8) is the second terminal (11) of the filter device (8) or is connected to the second line (4), wherein a sixth terminal (62) of the filter device (8) is the third terminal (12) of the filter device or is connected to the third line (6), wherein the filter device (8) further - a sixth capacitor (63) and a seventh capacitor (64), between which a second central node (65) with an electrically conductive connection to the sixth terminal (62) is formed, - an eighth capacitor (66) connected between a terminal (63a) of the sixth capacitor (63) facing away from the second central node (65) and the fourth terminal (60) of the filter device (8), - a ninth capacitor (67) connected between a terminal (64b) of the seventh capacitor (64) facing away from the second central node (65) and the fifth terminal (61) of the filter device (8), and - a second switching device (69) which is configured to switch between the first filter mode and the second filter mode of the filter device (8) depending on the control information (20), wherein a third current path (71) for the interference current on the first line (2) is formed from the fourth terminal (60) of the filter device (8) via the eighth capacitor (66), a parallel circuit of the sixth capacitor (63) and the seventh capacitor (64) and the second center node (65) to the sixth terminal (62) of the filter device (8), wherein a fourth current path (72) for the interference current on the second line is formed from the fifth terminal (61) of the filter device (8) via the ninth capacitor (67), a parallel circuit of the sixth capacitor (63) and the seventh capacitor (64) and the second center node (65) to the sixth terminal (62) of the filter device (8),wherein in the second filter mode an admittance for the interference currents along the third current path (71) and the fourth current path (72) is at least reduced compared to the first filter mode.

13. A power converter according to claim 12 when dependent on claim 9, wherein - the capacitances (Ce, C9) of the sixth capacitor (63) and the ninth capacitor (67) are greater, in particular by at least a factor of two, in particular by at least a factor of five, than the capacitances (C7, Cs) of the seventh capacitor (64) and the eighth capacitor (66), if the capacitances of the first capacitor (13) and the fourth capacitor (17) are smaller than the capacitances (C2, C3) of the second capacitor (14) and the third capacitor (16), or - the capacitances (Ce, C9) of the sixth capacitor (63) and the ninth capacitor (67) are smaller, in particular by at least a factor of two, in particular by at least a factor of five, than the capacitances (C7, Cs) of the seventh capacitor (64) and the eighth capacitor (66) when the capacitances of the first capacitor (13) and the fourth capacitor (17) are greater than the capacitances (C2, C3) of the second capacitor (14) and the third capacitor (16).

14. Power converter according to one of the preceding claims, wherein the filter device (8) comprises a printed circuit board (50), wherein - the first to fourth capacitors (13, 14, 16, 17), in particular also the fifth capacitor (28) and / or the sixth to ninth capacitors (63, 64, 66, 67), are arranged on the printed circuit board (50) and / or - the first to third terminals (10, 11, 12) of the filter device (8) are arranged on the printed circuit board (50) and / or - the switching device (19) or the switching devices (19, 69) is arranged on the printed circuit board (50), and / or the power converter (1 ) further comprises an intermediate circuit capacitor (40) which is connected between the first line (2) and the second line (4) and in particular has a capacitance which is at least one hundred times, preferably five hundred times, greater than the largest capacitance (Ci, C2, C3, C4) of the first to fourth capacitors (13, 14, 16, 17), and a converter circuit (41 ) which is connected between the first line (2) and the second line (4), wherein the filter device (8) is arranged on the side of the intermediate circuit capacitor (40) facing away from the converter circuit (41 ).

15. On-board electrical system (101) for an electrically driven vehicle (100), comprising at least one power converter (1, 1a, 1b) according to one of the preceding claims, a traction battery (102), a charging device (103) which can be connected to an electrical network (104) external to the vehicle for charging or discharging the traction battery (102), and a control device (105) which is designed to provide the control information (20) for adopting the second filter mode if and / or as long as the charging device (103) is connected to the electrical network (104) external to the vehicle.

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